Temperature responsive electrical switch

ABSTRACT

A temperature responsive electrical switch which includes a temperature calibrated pressure gauge employing a gas-filled sealed temperature sensing assembly comprising a bourdon tube connected to a thermal bulb by means of a tubular conduit. Enclosed within the housing of the temperature responsive electrical switch is electrical switch means which makes or breaks contact in response to variations in temperature at the thermal bulb which in turn causes motion of the bourdon tube. Means are disclosed for mechanically linking the bourdon tube to the electrical switch means to open or close the contacts of the switch means in response to temperature variations. Means are also disclosed for adjusting the electrical switch means so that the electrical switch means will open or close at a precise temperature which is visually displayed on the temperature responsive electrical switch.

United States Patent Stockton Apr. 8, 1975 [76] Inventor: Harold E.Stockton, 700 Ashley Dr.,

Moore, Okla. 73160 [22] Filed: May 16, I973 [21] Appl. No: 360,68l

Related US. Application Data [63] Continuation'in-part of Ser. No.326.516, Jan. 24.

[52] US. Cl 73/368.6; ZOO/81.8 [51] Int. Cl. ..G01k 5/36 [58] Field ofSearch 73/3686, 389, 411; ZOO/81.8, 56 R; 340/229 [56] References CitedUNITED STATES PATENTS 670,999 4/1901 Purinton et a1. ZOO/81.8 1,290,9281/1919 Denison ZOO/81.8 1.504.848 /1924 Trova 73/368!) PrimaryE.\'aminerDonald O. Woodiel Attorney, Agent, or FirmLaney, Dougherty,Hessin & Fish [57] ABSTRACT A temperature responsive electrical switchwhich includes a temperature calibrated pressure gauge employing agas-filled sealed temperature sensing assembly comprising a bourdon tubeconnected to a thermal bulb by means of a tubular conduit. Enclosedwithin the housing of the temperature responsive electrical switch iselectrical switch means which makes or breaks contact in response tovariations in temperature at the thermal bulb which in turn causesmotion of the bourdon tube. Means are disclosed for mechanically linkingthe bourdon tube to the electrical switch means to open or close thecontacts of the switch means in response to temperature variations.Means are also disclosed for adjusting the electrical switch means sothat the electrical switch means will open or close at a precisetemperature which is visually displayed on the temperature responsiveelectrical switch.

8 Claims, 11 Drawing Figures TEMPERATURE RESPONSIVE ELECTRICAL SWITCHCROSS-REFERENCE TO RELATED APPLICATION This is a continuation-in-part ofco-pending application Ser. No. 326.516. filed Jan. 24. 1973.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates generally to electrical switches and. more particluarly, but notby way of limitation. to temperature controlled electrical switches.

2. Description of the Prior Art It has been found in the refrigerationand food processing industries, among other. that it is often necessaryto monitor the temperature in a particular mrdium so that if thetemperature reaches a dangerously high or low level corrective actioncan be taken. For this reason it is most important to monitor suchtemperatures with a highly reliable and accurate temperature gauge.However. it is also important that when such dangerous I or undesirabletemperatures are experienced action is immediately taken to correct theimproper conditions.

The prior art contains varios teachings of temperature responsiveelectrical switches involving the use of bi-metallic springs andswitches, but these devices have not proved accurate and reliable enoughfor many applications. Also. the range of temperature adjustment forbi-metallic temperature switches is somewhat limited.

While pressure gauges utilizing bourdontubes are considered to be highlyreliable and accurate. such devices in combination with electricalswitches are not currently found to be available.

SUMMARY OF THE INVENTION The present invention contemplates atemperature responsive electrical switch comprising a frame, and agas-filled sealed temperature sensing assembly comprising a bourbon tubemounted on the frame, a conduit having opposite ends and communicatingat one end thereof with the bourbon tube, and a thermal bulbcommunicating with the opposite end of the conduit. The switch alsoinlcudes a temperature calibrated planar dial carried by the frame. anindicator shaft journally supported by the frame normal to the dial withone end thereof extending through the dial, and pointer means fixedlysecured to the one end of the indicator shaft for rotating with theshaft in a plane parallel to the plane of the dial to indicate atemperature on the dial. The pinion gear is fixedly secured to theindicator shaft for rotation therewith.

A lever arm is pivotally secured to the frame intermediate the first andsecond end portions thereof and includes a gear sector formed on thefirst end portion thereof in meshing engagement with the pinion gear.The switch further includes rigid link means pivotally secured at oneend thereof to the second end portion of the lever arm and pivotallysecured to the opposite end thereof to the bourdon tube for transferringmotion from the bourdon tube the lever arm.

Also included are electrical switch means carried by the frame foralternatley opening and closing an electrical circuit, together withactuator means responsive to the motion of the lever arm for actuatingthe electrical switch means to alternately open and close the elcetricalcircuit.

The temperature responsive electrical switch further includes adjustingmeans operatively connected to the electrical switch means forselectively adjusting the switch means to alternately open and close theswitch means at a predetermined temperature. and indicator meansoperatively engaging the adjusting means for visually indicating thepredetermined temperature at which the switch means is adjusted toalternately open and close.

An object of the present invention is to provide a temperatureresponsive electrical switch which is accurate and reliable.

Another object of the present invention is to provide a temperatureresponsive electrical switch which may be precisely set to open or closean electrical switch at a predetermined temperature.

A further object of the present invention is to provide a temperatureresponsive electrical switch which is simple in design, inexpensive tomanufacture. rugged in construction, easy to use and efficient inoperation.

Other objects and advantages of the present invention will be evidentfrom the following detailed description when read in conjunction withaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevation view ofone form of the present invention with a portion thereof broken away toillustrate details of the interior construction.

FIG. 2 is a side elevation view of the apparatus of FIG. 1 with portionsof the housing broken away to illustrate the internal construction ofthe apparatus.

FIG. 3 is an enlarged cross-sectional view taken along line 33 of FIG.1.

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 2.

FIG. 5 is a front elevation view of another form of the presentinvention with a portion thereof broken away to more clearly illustratethe internal construction thereof.

FIG. 6. is an enlarged partial front elevation view of the apparatus ofFIG. 5.

FIG. 7 is a front elevation view of another form of the presentinvention with a portion thereof broken away to more clearly illustratethe details of the interior construction thereof. I

FIG. 8 is a side-elevation view of the apparatus of FIG. 7 with portionsof the housing broken away to more clearly illustrate the details of theinterior construction thereof.

FIG. 9 is a partial rear elevation view of the apparauts of FIG. 7 tomore clearly illustrate the adjusting means thereof.

FIG. 10 is a front elevation view of another form of the presentinvention with a portion thereof broken away to more clearly illustratethe details of the internal construction thereof.

FIG. 11 is a partial front elevation view of the apparatus of FIG. 10more clearly illustrating the adjusting means thereof.

DESCRIPTION OF THE EMBODIMENT OF FIGS. 1, 2, 3 AND 4 Referring now tothe drawings, and to FIGS. 1, 2, 3 and 4 in particular, the temperatureresponsive electrical switch of the present invention is generallydesignated by the reference character 10. The switch comprises a mainsupport frame 12 which supports a sealed temperature sensing assembly14.

The temperature sensing assembly 14 comprises a C- shaped closed bourdontube 16 mounted on the main support frame 12, a tubular conduit 18having opposite ends and communicating at one end thereof with thebourdon tube 16 through a passageway (not shown) formed in the mainsupport frame 12, and a thermal bulb 20 which communicates with theopposite end of the tubular conduit 18. The bourdon tube 16, tubularconduit 18, and thermal bulb 20 form a sealed envelope in which asuitable gas is contained such that variations in temperature applied tothe thermal bulb 20 will result in movement of the bourdon tube 16 in aconventional, well-known manner. The temperature sensing assembly 14 maysuitably contain a number of different gases, e.g., mercury, argon,freon, etc.. depending upon the desired temperature range. The operativerange may be selected from the cryogenics temperatures up through 1000F.

A temperature calibrated planar dial 22 is rigidly mounted on the frontportion of the main support frame 12. An indicator shaft 24 is journallysupported at one end 26 thereof in the rear portion of the main supportframe 12 by means of suitable bearings 28. The axis of the indicatorshaft 24 is aligned normal to the plane of the dial 22 and the outer end30 of the shaft 24 extends through an aperture 32 formed in the dial 22.A temperature indicating pointer 34 is rigidly secured to the outer end30 of the shaft 24 and is adapted to rotate with the shaft 24.

A pinion gear 36 is nonrotatably secured to the shaft 24 and isseparated from the rear portion of the main support frame 12 by asuitable spacer 38. A second pinion gear 40 is coaxially journallysupported on the indicator shaft 24 and is free to rotate thereon. Thepinion gear 40 is separated from the pinion gear 36 by means of asuitable spacer 42. A tubular extension 44 is integrally formed on thepinion gear 40 and is coaxially aligned with the shaft 24. The tubularextension 44 extends through the previously mentioned aperture 32 in thedial 22. An indicator pointer 46 is rigidly secured to the tubularextension 44 intermediate the planar dial 22 and the temperatureindicating pointer 34.

A lever arm 48 is pivotally secured to the main support frame 12intermediate the first and second end portions SO-and 52 thereof. A gearsector 54 is formed on the first end portion of the lever arm 48 andmeshingly engages the pinion gear 36. A rigid link 56 is pivotallysecured at one end 58 thereof to the second end portion 52 of the leverarm 48. The opposite end 60 of the link 56 is pivotally secured to theouter end 62 of the bourdon tube 16.

A fan gear 64 is pivotally secured at its medial portion 66 to the mainsupport frame 12 by means ofa fan gear support shaft 68 which is fixedlysecured at one end 70 thereof to the main support frame 12. The fan gear64 is spaced from the main support frame 12 by means of a suitablespacer 72. The fan gear support shaft 68 is aligned substantiallyparallel to the indicator shaft 24.

An adjusting shaft 74 is journally supported at one end 76 .thereof bythe main support frame 12. The opposite end portion 78 extends throughan aperture 80 formed in the dial 22. A pinion gear 82 is nonrotatinglysecured to the adjusting shaft 72 intermediate the dial 22 and the mainsupport frame 12.

An upper gear sector 84 if formed on the fan gear 64 and meshinglyengages the previously mentioned pinion gear 40. A lower gear sector 86is also formed on the fan gear 64 and meshingly engages the pinion gear82. An arm 88 is formed on the fan gear 64 proximate to the upper gearsector 84 and extends outwardly therefrom.

A first electrical contact 90 is fixedly secured to the second endportion 52 of the lever arm 48. The first electrical contact 90 iselectrically insulated from the lever arm 48. A second electricalcontact 92 is mounted on the outer end portion 94 of the arm 88 by meansof a flat spiral overtravel spring 96 and a rigid pin member 98 whichinterconnects one end of the spring 96 and the outer end portion 94 ofthe arm 88. The second electrical contact 92 is electrically insulatedfrom the spring 96 and the arm 88.

A housing 100 encloses the structure thus far described, with theexception of the conduit 18 and the thermal bulb 20. The housing 100includes a transparent dial window 102 and a window retaining ring 104which secures the dial window 102 in place adjacent to the dial 22 tofacilitate visual recognition of the temperature values being indicatedon the dial 22. The end portion 78 of the adjusting shaft 74 extendsthrough an aperture 106 formed in the transparent dial window 102. Anadjusting knob 108 is nonrotatingly secured to the end portion 78 of theadjusting shaft 74 to provide means for manually adjusting thetemperature responsive electrical switch 10 without entry into thehousing 100. The housing 100 is suitably secured to the frame 12 bymeans of threaded screws 110 or other suitable means.

The first and second electrical contacts 90 and 92 are electricallyconnected to electrical conductors 112 and 114, respectively. whichconductors extend therefrom through a suitably insulated port 116 in thehousing 100 where they may be connected at their opposite ends to asuitable electrical circuit external to the housing 100.

OPERATION OF THE EMBODIMENT OF FIGS. 1, 2, 3 AND 4 During operation ofthe temperature responsive electrical switch 10, the thermal bulb 20 isplaced in the particular medium the temperature of which is to bemonitored. An increase in the temperature of the par-- ticular mediumcauses an expansion of the gas contained in the sealed temperaturesensing assembly 14 thereby causing the outer end 62 of the bourdon tube16 to move outwardly relative to the frame 12. This movement of thebourdon tube is transmitted through the rigid link 56 to the second endportion 52 of the lever arm 48 causing counterclockwise motion of thelever arm 48 about its pivotal connection with the main support frame 12as viewed in FIG. 1. The temperature indicating pointer 34 is therebydriven in a clockwise direction as viewed in FIG. 1 through the actionof the gear sector 54 driving the pinion gear 36 and the indicator shaft24. It will be readily apparent that a lowering of the temperature ofthe medium will cause the outer end 62 of the bourdon tube 16 to moveinwardly thereby causing the pointer 34 to move in a counterclockwisedirection through the action of the previously mentioned elements.

The temperature at which the switch contacts 90 and 92 will engage oneanother may be readily adjusted by turning the adjusting knob 108thereby rotating the fan gear 64 on the shaft 68 by means of the piniongear 82 on the adjusting shaft 74. By turning the adjusting knob 108 ina counterclockwise direction, as viewed in FIG. 1, it will beseen thatthe electrical contacts 90 and 92 will be moved relatively towardanother thereby allowing them to make contact at a lower mediumtemperature. Conversely, turning of the adjusting knob 108 in aclockwise direction moves the electrical contacts 90 and 92 furtherapart thereby requiring a higher medium temperature before the contacts90 and 92 will engage one another. The inherent resiliance of theovertravel spring 96 permits the switch to continue to indicate highertemperature after the contacts 90 and 92 have closed.

Adjustment of the adjusting knob 108 simultaneously causes movement ofthe indicator pointer 46 relative to the dial 22. This movementof theindicator pointer 46 is occasioned by the rotation of the pinion gear 40by the fan gear 64 in response to rotation of the adjusting knob 108.

Thus, it will be seen that the temperature responsive electrical switch10 permits the precise selection of a medium termperature at which pointthe electrical contacts 90 and 92 will engage one another therebycompleting a connection between the electrical conductors 112 and 114,and provides a clear visual indication of the particular temperature atwhich the electrical contacts 90 and 92 are to close.

DESCRIPTIONCF THE EMBODIMENT OF FIGS. 5 AND6 opposite ends andcommunicating at one end thereof with the bourdon' tube 126 through apassageway (not shown) formed in the main support frame 122, and athermal bulb (not shown), substantially identical to the thermal bulbdescribed above, which communicates with the opposite end of the tubularconduit 128. The boundon tube 126, tubular conduit 128, and theremalbulb form a sealed envelopein whch a suitable gas is contained asdescribed above for the sealed temperature sensing assembly 14.

A temperature calibrated planar dial 130 is rigidly mounted on the frontportion of the. main support frame 122. An indicator shaft 132 isjournally supported at one end'thereof in the rear portion of the mainsupport frame 122 by means of suitable bearings. The axis of theindicator shaft 132 is aligned normal to theplane of the dial 130 andthe outer end of the shaft 132 extends through an aperture formed inthedial 130. A temperature indicating pointer 134 is rigidlysecuredtothe 'outer end of he indicatorshaft 132 and is adapted to rotate withshaft .l32.-A pinion gear l36'is nonrotatably secured to the shaft-132.Y A

A lever arm 138 is pivotally secured to the main support frame 122intermediate the first and second end portions 140 and 142 thereof. Agear sector 144 is formed on the first end portion 140 of the lever arm138 and meshingly engages the pinion gear 136. A rigid link 146v ispivotally secured secured at one end 148 thereof to the second endportion 142 of the lever arm 138. The opposite end 150 of the link 146is pivotally secured to the outer end 152 of the bourdon tube 126.

A switch adjusting member 154 is pivotally secured at one end 156thereof to the main support frame 122. A gear sector 158 is formed onthe opposite end 160 of the switch adjusting member 154.

A contact support arm 162 is pivotally secured at the inner end 164thereof to the lever arm 138. A first electrical contact 166 is securedto the outer end 168 offthe contact support arm 162 and is electricallyinsulated therefrom. A tension coil overtravel spring 170 extendsbetween the second end portion 142 of the lever arm 138 and the contactsupport arm 162 intermediate the inner and outer ends 164 and 168thereof. A second electrical contact 172 is secured to the opposite end160 of the switch adjusting member 154 and is electrically insulatedtherefrom.

A housing 174 encloses the structure thus far described, with theexception of the conduit 128 and the thermal bulb,(not shown). Thehousing 174 includes a transparent dial window 176 and a windowretaining ring 178 which secures the dial window 176 in place adjacentto the dial 130 to facitlitate visual recognition of the temperaturevalues being indicated on the dial 130.

An adjusting shaft 180 is journally supported in the housing 174 withone end thereof extending through suitable apertures formed in the dial130 and the dial window 176. A pinion gear 182 is nonrotatingly securedto the adjusting shaft 180 and meshingly engages the gear sector 158 onthe switch adjusting member 154. An indicator pointer 184 isnonrotatingly secured to the adjusting shaft 180 intermediate the dial130 and the dial window 176. An adjusting knob 186 is nonrotatinglysecured to the adjusting shaft 180 just outside the dial windor 176where it may be onveniently grasped.

It will be seen in FIG. 5 that temperature indications are displayed onthe dial 130 which may be indicated by the temperature indicatingpointer 134. It will also be seen in FIG. 6 that additional temperatureindications are displayed on the dial 130 which may be inidicated by theindicator pointer 184.

The first and second electrical contacts 166 and 172 are electricallyconnected to electrical conductors 188 and 190, respectively, whichconductors extend therefrom through a suitably insulated port 192 in thehousing 174 where they may be connected at their opposite ends to asuitable electrical circuit external to the housing 174.

OPERATION OF THE EMBODIMENT OF- FIGS. 5

AND 6 I Operationof the temperature responsive electrical however, thatthe temperature at which the switch contact 166 and 172 will engage oneanother may be readily-adjusted by turning the adjusting knob 186thereby "rotating the switch adjusting member 154 about its pivotalconnection to the support frame 122 by'means of the pinion gear 182 onthe adjusting shaft 180. By turning the adjusting knob 186 in acounterclockwise direction as viewed in FIG. 6, it will be seen that theelectrical contacts 166 and 172 will be moved relatively toward oneanother thereby allowing them to make contact at 'a lower mediumtemperature. Conversely, turning of the adjusting know 186 in aclockwise direction moves the electrical contacts 166 and 172furtherapart thereby requiring a higher medium temperature before thecontacts 166 and 172 will engage one another. The inherent resiliance ofthe overtravel spring 170 permits the switch 120 to continue to indicatehigher temperatures after the contacts 166 and 172 have closed.

Adjustment of the adjusting knob 186 simultaneously causes movement ofthe indicator pointer 184 relative to the dial 130. This movement of theindicator pointer 184 is directly responsive to the movement of theadjusting knob 186.

Thus, it will be seen that the temperature responsive electrical switch120 permits the precise selectin of a medium temperature at which pointthe electrical contacts 166 and 172 will engage one another therebycompleting a connection between the electrical conductors 188 and 190,andiprovides a clear visual indication of the particular temperature atwhich the electrical contacts 166 and 172 are to close.

DESCRIPTION OF THE EMBODIMENT OF FIGS. 7, 8 AND 9 FIGS. 7, 8 and 9illustrate yet another form of temperature responsive electrical switchwhich will be generally designated by the reference character 200. Theswitch 200 is especially adapted for high explosion areas and comprisesa main support frame 202 which supports a sealed temperature sensingassembly 204.

The temperature sensing assembly 204 comprises a C-shaped, closesbourdon tube 206 mounted on the main support frame 202, a tubularconduit 208 having opposite ends and communicating at one end thereofwith the bourdon tube 206 through a passageway (not shown) formed in themain support frame 202, and a thermal bulb (not shown), substantiallyidentical to the thermal bulb described above, which communicates withthe opposite end of the tubular conduit 208. The bourdon tube 206,tubular conduit 208, and thermal bulb form a sealed envelope in which asuitable gas is contained as described above for the sealed temperatureassembly 14.

A temperature calibrated planar dial 210 is rigidly mounted on the frontportion of the main support frame 202. An indicator shaft 212 isjournally supported by the main support frame 202 and is alignedsubstantially normal to the plane of the dial 210. The outer end 214 ofthe shaft 212 extends through an aperture 216 formed in the dial 210. Atemperature indicating pointer 218 is rigidly secured to the outer end214 of the indicator shaft 212 and is adapted to rotate with the shaft212. A pinion gear 220 is nonrotatably secured to the shaft 212.

A lever arm 222 is pivotally secured to the main support frame 202intermediate the first and second end portions 224 and 226 thereof. Agear sector 228 is formed on the first end portion 224 of the lever arm222 and meshingly engages the pinion gear 220. A rigid ;202 and extendsgenerally downwardly therefrom. A

I conventional mercury switch 242 is secured to the lower end portion244 of the switch mounting member 238. The mercury switch 242 ispreferably of the type comprising a glass envelope of generallyelongated shape having a pair of contacts enclosed within the envelopewhich are alternately electrically connected and disconnected by meansof a small amount of mercury contained in the envelope in response tomovement of the switch envelope.

An adjusting shaft 246 is journaled in the enlarged medial portion 248of the switch mounting member 238. A cam 250 having an eccentric camsurface is nonrotatably secured to the inner end portion 252 of theadjusting shaft 246. The cam 250 engages the second end portion 226 ofthe lever arm 22. This engagement is maintained by means of a tensioncoil spring 254 interconnecting the lower end portion 244 of the switchmounting member 238 and the main support frame 202, which springconstantly biases the cam 250 into contact with the second end portion226 of the lever arm 22.

An indicator pointer 256 is nonrotatably secured to the adjusting shaft246 adjacent to the rear surface of the enlarged medial portion 248 ofthe switch mounting member 238. It will be seen in FIG. 9 that suitabletemperature indications are displayed on the rear surface of theenlarged medial portion 248 of the switch mounting member 238 which maybe indicated by the indicator pointer 256. These temperature indicationscorrespond to the temperature indications displayed on the dial 210 asillustrated in H6. 7.

A sealed housing 258 encloses the structure thus far described with theexception of the conduit 208 and the thermal bulb (not shown), and soenables safe usage in explosion incident areas. The housing 258 includesa transparent dial window 260 and a window retaining ring 262 whichsecures the dial window 260 in place adjacent to the dial 210 tofacilitate the visual recognition of the temperature values displayed onthe dial 210. An aperture 264 is formed in the rear portion of thehousing 258 through which the outer end portion 266 of the adjustingshaft 246 extends. The aperture 264 is sufficiently large to readilypermit the visual inspection of the position of the indicator pointer256 relative to the temperatures displayed on the medial portion 248 ofthe switching mounting member 238.

An adjusting knob 268 is nonrotatably secured to the outer end portion266 of the adjusting shaft 246 just to the rear of the housing 258. Theposition of the adjusting knob 268 provides a convenient point of graspfor the adjusting of the temperature responsive electrical switch 200.

First and second electrical conductors 270 and 272 are connected to therespective contacts of the mercury switch 242 and extend through thehousing 258 in v a manner substantially identical to that described indetail above for the switch 10 to a suitable electrical circuit externalto the housing 258.

OPERATION OF THE EMBODIMENT OF FIGS. 7, 8 AND 9 Operation of thetemperature responsive electrical switch 200 is substantially identicalto the operation previously described for the electrical switch 10 andneed not be described again in detail. It should be noted however thatthe temperature at which the mercury switch 242 will close may bereadily adjusted by turning the adjusting knob 268 thereby rotating thecam 250 about the axis of the adjusting shaft 246 thereby rotating theswitch mounting member 238 about its pivotal connection to the supportframe 202. The cam 250 is so positioned on the adjusting shaft 246relative to the position of the indicator pointer 256 that rotation ofthe adjusting knob 268 in a counterclockwise direction as viewed in FIGv9 will adjust the position of the mercury switch 242 such that it willclose at a higher medium temperature. Conversely, turning the adjustingknob 268 in a clockwise direction will cause the mercury switch 242 toclose at a lower medium temperature.

Adjustment of the adjusting knob 268 causes simultaneous movement of theindicator pointer 256 relative to the enlarged medial portion 248 of theswitch mounting member 238. This movement of the indicator point 256 isdirectly responsive to the movement of the adjusting knob 268.

Thus, it will be seen that the temperature responsive electrical switch200 permits the precise selection of a medium temperature at which pointthe mercury switch 242 willclose thereby completing a connection betweenthe electrical conductors 270 and 272, and provides a clear visualindication of the particular temperature at which the mercury switch 242is to close.

DESCRIPTION OF THE EMVODIMENT OF FIGS. 10 AND 11 FIGS. 10 and 11illustrate another form of temperature responsive electrical switchwhich will be generally designated by the reference character 280. Theswitch 280 comprises a main support frame 282 which supports a sealedtemperature sensing assembly 284.

The temperature sensing assembly 284 comprises a C-shaped, closedbourdon tube 286 mounted on the main support frame 282, a tubularconduit 288 having opposite ends and communicating at one end thereofwith the bourdon tube 286 through a passageway (not shown) formed in themain support frame 282, and a thermal bulb (not shown), substantiallyidentical to the thermal bulb described above, which communicates withthe opposite end of the tubular conduit 288. The bourdon tube 286,tubular conduit 288 and and thermal buld form a sealed envelope in whicha suitable gas is contained as described above for the sealedtemperature sensing assembly 14.

A temperature calibrated planar dial 290 is rigidly mounted on the frontportion of the main support frame 282. An indicator shaft 292 isjournally supported at one end thereof in the rear portion of the mainsupport frame 282 by means ofa suitable bearing. The axis of theindicator shaft 292 is aligned normal to the plane of the dial 290 andthe outer end of the shaft 292 extends through an aperture formed in thedial 290. A temperature indicating pointer 294 is rigidly secured to theouter end of the indicator shaft 292 and is adapted to rotate with theshaft 292. A pinion gear 296 is nonrotatably secured to the shaft 292.

A lever arm 298 is pivotally secured to the main support frame 282intermediate the first and second end portions 300 and 302 thereof. Agear sector 304 is formed on the first end portion 300 of the lever arm298 and meshingly engages the pinion gear 296. A rigid link 306 ispivotally secured at one end 308 thereof to the second end portion 302of the lever arm 298. The opposite end 310 of the link 306 is pivotallysecured to the outer end 312 of the bourdon tube 286.

A switch adjusting member 314 is pivotally secured at the medial portion316 thereof to the main support frame 282. A gear sector 318 is formedon the lower end 320 of the switch adusting member 314.

A conventional snap-action switch 322 is rigidly secured to the upperend portion 324 of the switch adjusting member 314. A switch-actuatingcam follower 326 is mounted on the snap-switch 322. The cam follower 326includes a cam-contacting surface 328 supported by a leaf spring 330extending between the camcontacting surface 328 and the snap-switch 322.A suitable snap-switch for the use in this application is manufacturedand sold under the trademark Microswitch.

The cam-contacting surface 328 of the snap-switch 322 is engaged by acam surface 332 formed on the first end portion 300 of the lever arm 298adjacent to the gear sector 304. An adjusting shaft 334 is journallysupported by the support frame 282 and is aligned substantially parallelto the indicator shaft 292. The adjusting shaft 334 extends through anaperture formed in the dial 290. A pinion 336 is nonrotatably secured tothe adjusting shaft 334 and meshingly engages the gear sector 318 formedon the switch adjusting member 314.

A housing 338 encloses the structure thus far described, with theexception of the conduit 288 and the thermal bulb (not shown). Thehousing 338 includes a transparent dial window 340 and a windowretaining ring 342 which secures the dial window 340 in place adjacentto the dial 290.

An indicator pointer 344 is nonrotatably secured to the adjusting shaft334 intermediate the dial 290 and the dial window 340. An adjusting knob346 is nonrotatably secured to the adjusting shaft 334 just outside thedial window 340 through which the adjusting shaft 334 extends.

It will be seen in FIG. 10 that temperature indications are displayed onthe dial 290 which may be indicated by the temperature indicatingpointer 294. It will also be seen in FIG. 11 that additional temperatureindications are displayed on the dial 290 which may be indicated by theindicator pointer 344.

First and second electrical conductors 348 and 350 are connected to theterminals of the snap-switch 322 and extend therefrom through a suitableinsulated port (not shown) in the housing 338 in a manner as describedin detail above for the temperature responsive electrical switch 10. Theconductors 348 and 350 may be connected at their opposite ends to asuitable electrical circuit external to the housing 338.

OPERATION OF THE EMBODIMENT OF FIGS. 10 AND 11 Operation of thetemperature responsive electrical switch 280 is substantially identicalto the operation previously described for the electrical switch 10 andneed not be described in detail again. It should be noted, however, thatthe temperature at which the snap-switch 322 will close may be readilyadjusted by turning the adjusting knob 346 thereby rotating the switchadjusting member 314 about its pivotal connec tion to the support frame282 by means of the pinion gear 336 engaging the gear sector 318. Byturning the adjusting knob 346 in a counterclockwise direction, asviewed in FIG. 11, it will be seen that the camcontacting surface 328will be moved relatively away from the cam surfaces 332 therebyrequiring a higher medium temperature before the switch 322 is closed bythe action of the cam surface 332 acting through the cam follower 326.Conversely, turning the adjusting knob 346 in a clockwise directionmoves the camcontacting surface 328 relatively toward the cam surface332 thereby allowing the switch 322 to close at a lower mediumtemperature. The inherent resiliance of the leaf spring 330 of the camfollower 326 permits the temperature responsive electrical switch 280 tocontinue to indicate higher temperatures after the switch 322 closes.

Adjustment of the adjusting knob 346 simultaneously causes movement ofthe indicator pointer 344 relative to the dial 290. This movement of theindicator pointer 344 is directly responsive to the movement of theadjusting knob 346. Thus, it will be seen that the temperatureresponsive electrical switch 280 permits the precise selection of amedium temperature at which point the snap-switch 322 will close therebycompleting a connection between the electrical conductors 348 and 350,and provides a clear visual indication of the particular temperature atwhich the snap-switch 322 is to close.

it will be readily apparent to those skilled in the art that the variousembodiments of the present invention described above can be readilyadapted and adjusted to open or close the electrical switch contacts ata precise predetermined temperature as the medium tempera ture is eitherincreasing or decreasing in value. The opening or closing of suchelectrical switch contacts may be utilized to control some form ofaudible or visual alarm system or a refrigeration system on or off. Itwill also be apparent that the present invention readily fulfills thestated objects set forth above.

The present invention has been described generally in relation to themore usual temperature control applications, but it should be understoodthat similar types of switchgauges may be employed in diverse industrialapplications ranging from freight and warehousing usage through highlyexacting employ in such fields as Cryogenics. biomedics, chemicalindustries, etc.

Changes may be 'made in the combination and arrangement of the parts orelements as heretofore set forth in the specification and shown in thedrawings without departing from the spirit and scope of the invention.

What is claimed is:

l. A temperature responsive electrical switch comprising:

a frame;

a sealed hollow temperature casing assembly comprising a bourdon tubemounted on the frame, a conduit having opposite ends and communicatingat one end thereof with said bourdon tube, and a thermal bulbcommunicating with the opposite end of said conduit;

a temperature calibrated planar dial carried by said frame;

an indicator shaft journally supported by said frame normal to said dialwith one end thereof extending through said dial;

pointer means fixedly secured to the one end of said indicator shaft forrotating with said shaft in a plane parallel to the plane of said dialto indicate a temperature on said dial;

a pinion gear fixedly secured to said indicator shaft for rotationtherewith;

a lever arm pivotally secured to said frame intermediate the first andsecond end portions thereof and having a gear sector formed on the firstend portion thereof in meshing engagement with said pinion gear;

rigid link means pivotally secured at one end thereof to the second endportion of said lever arm and pivotally secured at the opposite endthereof to said bourdon tube for transferring motion from said bourdontube to said lever arm;

electrical switch means carried by said frame for alternately openingand closing an electrical circuit, said switch means consisting of afirst electrical contact mounted on the second end portion of said leverarm and a second electrical contact privotally supported on said frameand operatively connected to said adjusting means;

- actuator means responsive to the motion of said lever arm foractuating said electrical switch means to alternately open and close theelectrical circuit;

adjusting means operatively connected to said electrical switch meansfor selectively adjusting said switch means to alternately open andclose said switch means at a predetermined temperature; and

indicator means operatively engaging said adjusting means for visuallyindicating the predetermined temperature at which said switch means isadjusted to alternately open and close.

2. The temperature responsive electrical switch as defined in claim 1characterized further to include:

a housing substantially enclosing said frame, said bourdon tube, saidtemperature calibrated dial, said indicator shaft. said pointer means,said pinion gear, said lever arm, said rigid link means, said electricalswitch means, said actuator means, said adjusting means, and saidindicator means, said housing including a transparent dial windowadjacent to said temperature calibrated dial;

a control knob disposed outside said housing;

means extending through said housing and interconnecting said controlknob and said adjusting means for transmitting motion from said controlknob to said adjusting means; and

electrical conductor means connected to said electrical switch means andextending therefrom through said housing for electrically connectingsaid electrical switch means to an electrical circuit external to saidhousing.

3. In combination with a temperature indicator of the type whichincludes a housing supporting a bourdon tube which is in communicationwith a gas-filled temperature sensing bulb and connected by mechanicallinkage to impart rotary motion to a temperature indicator, anelectrical control device comprising:

first contact means secured insulatively for movement in response tomovement of said mechanical linkage, said first contact means consistingof an arm means having first and second ends and being pivotally mountedwithin said housing, with one end connected to said mechanical linkageand the other end reciprocally moved in response thereto. and anelectrical Contact means resiliently secured to said arm means one end;

second contact means secured insulatively and intermittently movablywithin said housing, said second contact means being aligned forelectrically conductive contact with said first contact means at apreselected temperature; and

first and second conductor means leading from respective first andsecond contact means for external connection.

4. An electrical control device as set forth in claim 3 wherein saidfirst contact means comprises:

lever means centrally pivotally secured in said housing with one endconnected to said mechanical linkage and having an insulatively securedcontact mounted thereon, and with the other end connected to providerotary motion to said temperature indicator. 5. An electrical controldevice as set forth in claim 3 wherein:

said indicator is secured to an indicator shaft and pinion gearjournally supported within said housing; and said lever arm means otherend is formed as a sector gear in mesh with said pinion gear. 6. Anelectrical control device as set forth in claim 3 wherein:

said second contact means is intermittently movable by adjustmentcontrol to pre-select a temperature at which said first and secondcontact means make conductive contact. 7. An electrical contact deviceas set forth in claim 6 which is further characterized to include:

second indicator means actuated by said second contact means adjustmentcontrol to indicate continually said pre-selected temperature. 8. Anelectrical control device as set forth in claim 3 wherein said secondcontact means comprises:

arm means pivotally mounted and intermittently movable within saidhousing to extend a support arm; spring means secured to said supportarm; and electrical contact means securely supported by said springmeans in alignment for contact with said first contact means.

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No- 3,875,800 Dated April 8, 1975 Inventor(s) Harold E. Stockton It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

' Column 1, line 16 change "mrdium" to -medium-; 1

Column 1, line 26, change "varios" to various-; Column 1, line 46,change "inlcudes" to -inclu des;

Column 1, line 66, change 'alternatley" to alternately;

Column 2, line 53, change "apparauts" to apparatus-;

Column 4, line 3, change "if" to -is; 0

Column 5, line 10, after "toward" insert -one--;

Column 5, line 52, change "theremal" to thermal--;

Column 5, line 65, change "he" to -the; Column 6, line 6, delete one ofthe words "secured" Column 6, line 30, change "facitlitate" to--facilitate;

Column 6, line 44', change "windor" to window and change "onveniently"to conveniently;

Column 6, lines 49-50, change "inidicated" to -indicated-;

Column 7, line 9, change "know" to -knob-;

Column 7, line 23, change "select in" to --'sel,ection--;

Column 7, line 40, change "closes" to closed-;

Column 7, line 51, after "ture" insert sensing--;

Page 2 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.2,11%"? Da ed April 8, 1975 Inventor(s) It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Column 8, line 55, change "switching" to -switch--;

Column 9, line 37 change "EMVODIMENT" to EMBODIMENT;

"Tolumn 9, line 55, change "buld" to -bulb-;

Column 10, line 32, after "pinion" insert -gear-; Column 11, line 10,change "surfaces" to'-surface-- Column 12, line 26, change "privotally"to --pivotally-;

Column 14, line 3, delete "lever".

Signed and Scaled this twenty-second Day Of July 1975 [SEAL] Arrest:

RUTH C MASON (f. MARSHALL DANN Arresting Officer Commissioner of Parentsand Trademarks

1. A temperature responsive electrical switch comprising: a frame; asealed hollow temperature casing assembly comprising a bourdon tubemounted on the frame, a conduit having opposite ends and communicatingat one end thereof with said bourdon tube, and a thermal bulbcommunicating with the opposite end of said conduit; a temperaturecalibrated planar dial carried by said frame; an indicator shaftjournally supported by said frame normal to said dial with one endthereof extending through said dial; pointer means fixedly secured tothe one end of said indicator shaft for rotating with said shaft in aplane parallel to the plane of said dial to indicate a temperature onsaid dial; a pinion gear fixedly secured to said indicator shaft forrotation therewith; a lever arm pivotally secured to said frameintermediate the first and second end portions thereof and having a gearsector formed on the first end portion thereof in meshing engagementwith said pinion gear; rigid link means pivotally secured at one endthereof to the second end portion of said lever arm and pivotallysecured at the opposite end thereof to said bourdon tube fortransferring motion from said bourdon tube to said lever arm; electricalswitch means carried by said frame for alternately opening and closingan electrical circuit, said switch means consisting of a firstelectrical contact mounted on the second end portion of said lever armand a second electrical contact privotally supported on said frame andoperatively connected to said adjusting means; actuator means responsiveto the motion of said lever arm for actuating said electrical switchmeans to alternately open and close the electrical circuit; adjustingmeans operatively connected to said electrical switch means forselectively adjusting said switch means to alternately open and closesaid switch means at a predetermined temperature; and indicator meansoperatively engaging said adjusting means for visually indicating thepredetermined temperature at which said switch means is adjusted toalternately open and close.
 2. The temperature responsive electricalswitch as defined in claim 1 characterized further to include: a housingsubstantially enclosing said frame, said bourdon tube, said temperaturecalibrated dial, said indicator shaft, said pointer means, said piniongear, said lever arm, said rigid link means, said electrical switchmeans, said actuator means, said adjusting means, and said indicatormeans, said housing including a transparent dial window adjacent to saidtemperature calibrated dial; a control knob disposed outside saidhousing; means extending through said housing and interconnecting saidcontrol knob and said adjusting means for transmitting motion from saidcontrol knob to said adjusting means; and electrical conductor meansconnected to said electrical switch means and extending therefromthrough said housing for electrically connecting said electrical switchmeans to an electrical circuit external to said housing.
 3. Incombination with a temperature indicator of the type which includes ahousing supporting a bourdon tube which is in communication with agas-filled temperature sensing bulb and connected by mechanical linkageto impart rotary motion to a temperature indicator, an electricalcontrol device comprising: first contact means secured insulatively formovement in response to movement of said mechanical linkage, said firstcontact means consisting of an arm means having first and second endsand being pivotally mounted within said housing, with one end connectedto said mechanical linkage and the other end reciprocally moved inresponse thereto, and an electrical contact means resiliently secured tosaid arm means one end; second contact means secured insulatively andintermittently movably within said housing, said second contact meansbeing aligned for electrically conductive contact with said firstcontact means at a preselected temperature; and first and secondconductor means leading from respective first and second contact meansfor external connection.
 4. An electrical control device as set forth inclaim 3 wherein said first contact means comprises: lever meanscentrally pivotally secured in said housing with one end connected tosaid mechanical linkage and having an insulatively secured contactmounted thereon, and with the other end connected to provide rotarymotion to said temperature indicator.
 5. An electrical control device asset forth in claim 3 wherein: said indicator is secured to an indicatorshaft and pinion gear journally supported within said housing; and saidlever arm means other end is formed as a sector gear in mesh with saidpinion gear.
 6. An electrical control device as set forth in claim 3wherein: said second contact means is intermittently movable byadjustment control to pre-select a temperature at which said first andsecond contact means make conductive contact.
 7. An electrical contactdevice as set forth in claim 6 which is further characterized toinclude: second indicator means actuated by said second contact meansadjustment control to indicate continually said pre-selectedtemperature.
 8. An electrical control device as set forth in claim 3wherein said second contact means comprises: arm means pivotally mountedand intermittently movable within said housing to extend a support arm;spring means secured to said support arm; and electrical contact meanssecurely supported by said spring means in alignment for contact withsaid first contact means.